1. Field of Invention
The present invention represents a method and apparatus for producing yarn, and more particularly to a method and apparatus for producing yarn of high quality, wherein an iron-heating apparatus is installed on existing ring spinning machines to achieve the desired quality of yarn.
2. Description of Related Arts
Hairiness is one of important indexes to measure the quality of yarn. Hairiness can affect not only subsequent efficiency of yarn production, but also the quality and appearance of the final product. Reducing hairiness is very significant especially when shuttle-free machines are widely used today.
Generally speaking, hairiness is generated during the process of yarn production, wherein hairiness will be increased in spinning process and reduced in sizing process. With regard to ring spinning machines, fibers are twisted in a so-called twisting triangle area so that they can be effectively enwrapped into yarn during spinning, and yarn hairiness is consequently generated. It is mainly because the yarn twisted in the front roller in the twisting triangle area is under torques. Torque of differing magnitudes is exerted on the outer and inner layers of the fiber. When the fiber is spun, if the torque is not large enough to overcome the rigidity of the fiber and made it bend to the center of the yarn, the fiber will become hairiness on the surface of the yarn. Moreover, hairiness can be formed at the very end of the fiber because the tension suddenly disappears at the exit of the twisting triangle area and the very end of the fiber can no longer be twisted into the fiber. It is generally believed that the physical property of the fiber is an important factor of hairiness in the process of yarn spinning. Hairiness can be reduced by longer or thinner fibers, enhancing the fineness of the fibers, increasing the number of twist of yarn or lowering the rigidity of the fiber.
Extensive researches regarding controlling hairiness have been conducted by many scholars. Two controlling methods are usually adopted: one is so-called ordinary methods and the other is the method of using hairiness-reducing equipment. Ordinary methods involve the process of optimization of certain industrial parameters or adopting some new techniques of yarn spinning to reduce hairiness, such as increasing the number of twist of yarn, lowering the speed of yarn spinning, appropriately increasing the tension of yarn spinning or decreasing the relaxation parameter in the area of spun yarn, or adopting the technology of compact yarn. Currently, the research is focused on adding some simple hairiness-reducing equipment on traditional ring spinning machines. An air-injection method is used so far in which the air-injection apparatus is installed between front roller and guide wire, so that the eddy of air flow can force the hairiness to stay close to the surface of yarn. This technique has been disclosed in “method and apparatus yarn treatment” patented on Apr. 10, 1974 (U.S. Pat. No. 4,148,179), and “method and apparatus for modifying spun textile yarn” patented on Aug. 22, 1989 (U.S. Pat. No. 5,263,311). Major difference in above researches is that each air-injection apparatus generates different directions of air flow which has different hairiness-reducing effect. However, these apparatuses can only be installed after the twisting triangle area, meaning that the hairiness has already been formed and it can only be forced to stay close to the surface of yarn, but cannot be eliminated. Furthermore, specific air compressors and pipelines are necessary for these apparatuses. It can greatly affect the operative in a textile mill when such air-injection apparatus is also installed on the yarn equipment.